Process for the coagulation of latex like emulsions to rubber like masses



methyl butadiene- (1.3) and other homologues vary in wide limits, mainly depending on the 'kind of the emulsifying agent used.

Patented Aug. 30, 1932 UNITED ST TES PATENT OFFICE- Y ERICK KGEBAD AND WERNER SIEFKEN, OF GOIQOGNE-IULKEIKHON-THE-BEHITIE, GER- MAN'Y, ASSIGNORS TO I. G'. FABBENINDUSTBIE AKTIENGESELLSCHAFT, 0F IRAQI! FOBT-ON-THE-MAIN, GERMANY, A OOEPOB-LTION OF GERMANY PROCESS FOR THE CO AGULATION 0F LATEX LIKE EHULSIONB TO RUBBER LIKE MASSES n'o'Drawing. Application filed January 4, 1989, Serial No. 336,426, and in Germany January 16, 192 8.

The present invention relates to a process of coagulating latex-like emulsions to rubberlike masses by causing the emulsions to freeze out.

Several methods for the manufacture of artificial rubber-like masses have already been the subject of patent applications, by which methods the starting hydrocarbons, such as butadiene-(L3), isoprene, 2.3-diand analogues of butadiene-(1.3), are emulsified in water in the presence of emulsif ing agents, such as soaps, alkali metal salts 0 bile acids and the like, and polymerized in this emulsion. By these processes there are frequently .obtained latex-like emulsions, from which the artificial rubber-like masses must be obtained by coagulation.

These latex-like emulsions can be coagulated, it is true, by analogous methods to those used with natural rubber latex, for example, by'means of acids. According to the present invention, however, a separation of the aqueous emulsifying solution and the dispersed,

hydrocarbon is effected simply by cooling the latex-like emulsions below the freezin point of the emulsion at least until the who e mass has frozen. This process will be-designated hereinafter as freezing out. The aqueous layer containing the emulsifyin agent can then be separated from the coagu ate by subsequent thawing.

.This method has the great advantage that the recovery of the emulsifying a ent is rendered possible in'the simplest and c eapest manner. Provided that the latex-like emulsion is not diluted prior tothe freezing out, the aqueous la er containing the emulsifying agent can be irectly used again for emulsifying and polymerizing a fresh quantit of hydrocarbon. Moreover the acid w ich would otherwise be necessary is saved, which is all the more im ortant, since the coagulation of some latexike emulsions requires considerable quantities of acid.

A further technical advance of our coagulation process is, that, after having separated the aqueous layer containing the emulsifying agent, the coagulate, after the washing an drawing, can be used for vulcanizing pur- 'on tothe partlcles of the emulsion containing poses without any further cleaning, whereas,

In some particular cases it has been found that the complete removal and recoveryof the emulsifying agent is rendered diflicult or occasionally impossible, that is to say, when the latex-like emulsions contain any unchanged diolefine. In such a case the emulsifying agent may be absorbed so firmly rubber and the unchanged diolefine, that it can only be removed incompletely even by repeate washing. This phenomenon seems to appear especially, when a colloidal emulsifying agent has been used, as for example, aqueous soap solution. When this hap ens, the complete recovery and removal 0 the emulsifying agent can be effected by removing the unc anged diolefine by evaporation or vaporization either before or after coolingthe emulsion. The evaporation can be effected in various ways, for example, by passing an indifferent gas through the latex or by rollin the coagulate. vaporization can also be e ected by any desired method, as for example, by simple heating or by recourse to reduced ressure.

The f0 owing examples will illustrate our invention without limiting it thereto, the parts being by weight.

Ewample 1 To parts of an aqueous 10% sodium I emulsion has formed and is then heated to 60 C. for about .3 days, while continually shaking. After that time 50% of the butadiene -(1.3) will be polymerized in the 10.

form ofaIatex-Iike emulsion which latter is removing an un 1 rized h a bo coagu15 latefd by cogllilng the emulsion to 'byIva orizatign. y n

or a cut ours. When thawing n on whereof we havehe unto t ..the unchanged butadiene will va orize. After our hands. y m I so the coagulate is pressed and washed, M a Y I ERICH KONRAD. i

until the adhering sodium oleate is removed. WERNEB SIEFKEN. Example 2 I Y 100 parts of isoprene are emulgated in 150 w parts of a 5% aqueous sodium desoxychol'ate a solution and this emulsion is heated to -70 C. for about 2 days while shaking; The latexlike emulsion thus obtained is freed from unchan ed isoprene by steam distillation, after whic the emulsion 1S cooled to about 20 C.

until the whole mass has solidified. After thawing, the coagulate is isolated and washed with water. I,

- Ewamplefi I parts of 2.3-dimethyl butadiene-(LB) are emulgated with arts of a warm [aqueous sodium stearate solution of 8% stren h and this emulsion is heated to 70 C.

35 for a ut 10 days while continual] shaking.

In a nearl quantitative yield a po ymerizate v of cream ike consistency is thus obtained which is diluted with the samej uantity of a warmwater-while stirring and t en cooled V ac to about -15 G. for 4 hours. After thawa ing, the coagulate'i's separateda'nd wished with warm water-i1 @Weclaim: v ,1. A process of manufacturing rubber-like 4 4 8i masses which comprises polymerizing a compound of the group consisting of butadiene- 8,8) and its methyl substitution products in e presence of water and of an emulsifying agent and then coagulating the latex-like g emulsions thus obtained by freezing out. I I

- 2. A process of manufacturing rubber-like m which comprises polymenzing a' com pound of the group consisting of butadiene- $1.3), isoprene and 2.3-dimethyl-butadiene- 1.8) in=the presence of water and of an emulsi a nt and then 'coa lating the latex-1i eemu sions thus obtains by freezing out a 8, of manufacturing rubber-like gi masses which comprises polymerizing a com pound of the group consisting of butadiene- (1.3) and its methyl substitution products in the presence of water and of an emulsifyino agent, coagulating the latex-like emulsions thus obtained by freezing outamd removing 1 any unpolymerized hydrocarbon by vaporization. y I, a 4. A process of manufacturing rubber-like I masses which comprises'polymerizing a compound ofthe group consisting ofb'utadiene- (1.3), isoprene and 2.3-dimethyl-b1itadiene- (1.8) in' the presence of water and of an emuls fying agent, coagulating the latex-like 85 emulsions thus obtained by freezing out and .3. 

